ISLAMABAD: Pakistan's former prime minister Imran Khan on Sunday won six out of eight National Assembly seats in by-elections, according to unofficial and unconfirmed results, which he recently described as "a referendum" on his popularity.

Khan was driven out of the office in a no-confidence vote in April after he lost his parliamentary majority. Since then, he held several public rallies across the country in which he claimed that he was ousted from power after an international conspiracy was hatched against him in Washington for pursuing an independent foreign policy.

The US administration has consistently denied the charge.

The former prime minister's Pakistan Tehreek-e-Insaf (PTI) party decided to resign from the National Assembly after the no-trust vote while demanding fresh elections in the country.

Khan's PTI also swept crucial Punjab Assembly by-elections in July which were held on 20 seats. Sunday's polls gave the party its second major electoral victory since the downfall of its administration earlier this year.

"Today, the biggest court of Pakistan – i.e. its people – has given its verdict," said Chaudhry Fawad Hussain, the ex-PM's close aide, in a Twitter post. "The contempt of this verdict will be unacceptable. The only leader of the nation is #ImranKhan."

The PTI has won from NA-22 Mardan, NA-31 Peshawar, NA-24 Charsadda, NA-108 Faisalabad-VIII, NA-118 Nankana Sahib and NA-239-Korangi. It has also bagged two Punjab provincial assembly seats from PP-209 Khanewal and PP-241 Bahawalnagar.

However, the party could not reclaim the National Assembly constituencies of NA-157 Multan-IV and Malir II.

All the National Assembly seats fell vacant after the resignations of PTI legislators were accepted by Speaker Raja Parvaiz Ashraf.

Even after sweeping the elections, a top PTI leader, Asad Umar, announced that his top party leader would not return to the National Assembly.

"Today's election was a referendum," he said in a statement quoted by Geo News. "Imran Khan will not return to the assembly after winning and he will not take the oath."

"Our only demand is to give people the right to vote," he continued.

Khan urged the people to step out and vote in the by-elections on Sunday, saying he was striving for the "real independence" of the country.

He also maintained he was contesting the elections against the ruling coalition and the entire state machinery.